syweb's default install assumes that:
  - web server is chrooted at ${PREFIX}
  - rrdtool is installed in the chroot
  - symux rrd files are kept in ${PREFIX}/symon/rrds/<host>/*.rrd

Customise ${PREFIX}/htdocs/syweb/setup.inc if these assumptions are
incorrect. rrdtool must also be copied into the chroot jail; for this,
see rrdtool's pkg-readme document.
